The present invention relates to a signal transmitting circuit and related method, and more particularly to a signal transmitter and system having low power consumption, and a related method for saving power consumption of the signal transmitter.
In a communication system, e.g., an optical fiber communication system, a transmitter is employed to transmit a data signal to a transmission medium, e.g., the optical fiber, in which the transmission medium is responsible for conveying the data signal to a receiver. To maximize the power transferring to the loading device, i.e., the transmission medium in combination with the receiver, a characteristic impedance of the transmitter (i.e., source impedance) should match with the characteristic impedance of the loading device (i.e., load impedance). In other words, the characteristic impedance of the transmitter should equal the characteristic impedance of the loading device. By doing this, however, the characteristic impedance of the transmitter consumes the same power as the power consumed by the characteristic impedance of the loading device. Accordingly, the power efficiency of the transmitter is reduced since not all of the power generated by the transmitter is transferred to the loading device. More seriously, when more power is transmitted to the loading device, more power is wasted by the characteristic impedance of the transmitter. Therefore, providing an efficient way to reduce the power consumption due to the source impedance of the transmitter is a significant concern in the communication system field.